Peltier element for precise temperature control in a sorption trap

Measuring volatile organic compounds (VOCs) is challenging because they occur in the air only in extremely low concentrations. A novel measurement system developed at Fraunhofer IPM combines a metal oxide sensor and a sorption trap operated by a Peltier element to reliably measure VOCs in air.

At low temperatures, specific gases adhere to certain sorbents, while rising temperature leads to desorbing of the gas. Due to the adsorption effect, the gas concentration at the sensor increases, which allows the gas concentration in room air to be determined. The temperature in the sorption trap is controlled by a Peltier element that enables fast and very accurate temperature ramps and thus improves the accuracy of the gas measurement.

Characterizing the system with specific gases proves that it is possible to detect even small changes in the sample gas by pre-concentrating low gas concentrations. The pre-concentrator consists of a Peltier element and sorbent in conjunction with a commercially available metal oxide gas sensor. It enables a small, cost-effective and long-term stable measurement system for analyzing low concentrations of volatile organic compounds in ambient air.